Fluidic control circuit for operating gas blast circuit breaker



United States Patent [72] Inventors Joseph T. Warnemuende 3,087,035 4/1963 Forwald 200/ 148.2 Milwaukee, Wisconsin; 3,250,285 5/1966 Vockroth,.lr. 137/815 Ralph O.Turnquist,Manhattan, Kansas 3,258,118 6/1966 Gesell 235/200(PF)UX [21] AppLNo. 780,794 3,280,288 10/1966 Frowein ZOO/148.2 [22] Filed Dec.3, 1968 3,443,575 5/1969 Hughes 137/815 [45] Patented Sept. 1, 1970 3,463,178 8/1969 Kirchmier 235/201(PF)UX [73] Assignee Allis-Chalmers Manufacturing Company 3,474,814 10/1969 Sher et a1 235/201X Milwaukee, Wisconsin Primary Examiner- Samuel Scott L B d H. 154 FLUlDlC CONTROL CIRCUIT FOR OPERATING fgf Thmas F Robert B enson an 66 GAS BLAST CIRCUIT BREAKER 8 Claims, 10 Drawing Figs.

[52] U.S.Cl 137/815;

91/3 ABSTRACT: A fluidic circuit for controlling a multiphase gas {51] Int-Cl Fl5c 3/02, blast circuit breaker which is operated by pressurized gas F159 H12 comprises fluidic components for actuating the circuit breaker [50] Fleld of Search 200/148; m mechanism and closing mechanism with pressurized gas 307/136; 235/20l,200; 137/81.5;9l/3 upon operator commands in the fluidic circuit, means for ignoring either command if gas supply pressure is below [56] References cued predetermined levels, and means for detecting whether or not UNITED STATES PATENTS the circuit breaker phases are all open or all closed and for ac- 2,964,605 12/1960 Schulz ZOO/148.2 tuating the trip mechanism in the event that all breakerphases 3,038,449 6/1962 Murphy,Jr.,et al 235/200 do not operate together.

40% P1765501?! flea/Par I it'd 4m? lZU/fl/CJ/F 3 jl/FfllYfiM/A I? J! F am-- Egg L zr(1 i Patented Sept. 1, 1970 Sheet l FLIIIDIC CONTROL CIRCUIT FOR OPERATING GAS BLAST CIRCUIT BREAKER circuit interrupter and a circuit isolator switch for each phase 1 or pole. These breakers have an operating mechanism comprising a trip cylinder and a close cylinder which effect simultaneous opening and simultaneous closing, respectively, of all circuit isolators when those cylinders are supplied with pressurized gas from a suitable source. Furthermore, each isolator chamber is pressurized with gas from the source when its isolator is open and depressurized when the isolator is closed.

l lere'tofore, pneumatic control means were provided for controlling gas flow to the close and trip cylinders of the operating mechanism and such means included, for example, manually operable pneumatic push buttons, pneumatic feedback mechanisms, pneumatic lockouts, spring loaded valves, and other pneumatic-mechanical components. While such pneumatic control means were generally satisfactory, they were expensive, hard to adjust, used moving parts which tended to stick and wear, and were large in size because they were operated by high pressure gas.

In accordance with the present invention, there is provided an improved fluidic control circuit which uses fluidic components, which circuit is particularly well suited to replace the aforedescribed pneumatic control means used with gas blast circuit breakers and other devices. This fluidic control circuit comprises means for manually controlling the gas supply to the trip cylinder and the close cylinder of the circuit breaker operating mechanism, means for ignoring these manual commands if gas supply pressure is below predetermined levels, means for detecting whether or not the isolators are all open or all closed, and means for actuating the circuit breaker trip mechanism in the event that all circuit breaker poles do not operate together.

OBJECTS It is an object of the present invention to provide improved fluidic control circuits using fluidic logic elements which are small, have no moving parts, operate at pressures of a few pounds per square inch, and may be used with inherently reliable interface devices.

Another object is to provide fluidic control circuits of the aforesaid character which are particularly well adapted to control operation of gas blast circuit breakers.

Another object is to provide fluidic control circuits of the aforesaid character which comprise means for manually effecting opening and closing of a circuit breaker and which further comprise means for preventing execution of such manual commands if gas supply pressure is below predetermined levels.

Another object is to provide fluidic control circuits of the aforesaid character which comprise means for detecting whether or not the circuit breaker isolators are all open or all closed.

Another object is to provide fluidic control circuits of the aforesaid character which comprise means for actuating a cir- DRAWINGS The accompanying drawings illustrate a preferred embodiment of the invention, but it is to be understood that the embodiment shown is susceptible of modifications with respect to details thereof without departing from the scope of the appended claims.

In the drawings:

FIG. I shows a normally closed fluidic pressure switch symbol; FIG. 2 shows a fluidic check valve symbol;

FIG. 3 shows a fluidic push button symbol;

FIG. 4 shows a fluidic OR-NOR gate symbol;

FIG. 5 shows a fluidic passive OR device symbol;

FIG. 6 shows a preferenced fluidic flip-flop symbol;

FIG. 7 shows a normally open fluidic pressure switch symbol;

FIG. 8 shows a fluidically actuated four-way valve symbol;

FIG. 9 shows a fluidic resistor symbol; and

FIG. 10 is a schematic diagram of a fluidic control circuit in accordance with the present invention which employs fluidic components symbolically shown in FIGS. 1 through 9.

DESCRIPTION OF THE INVENTION Referring to the drawings, FIGS. 1 through 9 are schematic diagrams or symbols of fluidic components used in the fluidic control circuit shown in FIG. 10 and generally corresponding fluid lines or points in each symbol are designated by the same letters.

FIG. 1 shows a normally closed fluidic pressure switch symbol wherein a pneumatic connection is made from A to B when pressure in the line C exceeds a given value. Removal of pressure in line C, results in the closing or blocking of the pneumatic path from A to B.

FIG. 2 shows a fluidic check valve symbol wherein air flow is allowed to go from A to B, but not from B to A.

FIG. 3 shows a fluidic push button symbol wherein a pneumatic connection between A and B is made when a push button is depressed. Otherwise no flow is possible between A and FIG. 4 shows a fluidic OR-NOR gate symbol. For operation of this device, an air supply must be connected at S. This supply is recovered at Y if pressure is present at any one of the control inputs, C, C". Otherwise, the supply pressure is recovered at X. Thus, the Y port may be considered logically Y=C or C or. .orC

In the circuit of FIG. 10, OR-NOR gates are used with one, two and three inputs. The output Y is called the OR leg and the output X is called the NOR leg of the gate.

FIG. 5 shows a fluidic passive OR device symbol. No supply is needed for this device. Air flow is delivered at C if pressure is present at either A or B.

FIG. 6 shows a preferenced fluidic flip-flop symbol. A supply of air is connected at S. Flow from this supply is recovered at either X or Y. If the output air flow is at X, it may be switched to Y by a pressure signal at control port B. A pressure signal at control port A will switch the output air flow to X. The output air flow will not change without a pressure signal at A or B. A signal at A will not affect an output at X and a signal at B will not change an output at Y. If the supply at S is removed and subsequently restored, in the absence of a signal at B, the output will initially appear at X. Thus, output X is called the preferenced leg of the flip-flop.

FIG. 7 shows a normally open fluidic pressure switch symbol wherein the pneumatic path from A to B is closed or blocked when the pressure in the line C exceeds a given value. Removal of pressure in line C results in the reopening of the pneumatic path from A to B.

FIG. 8 shows a fluidically actuated four-way valve symbol. A pneumatic connection is normally present between A and B and between C and D. A pressure signal at X will cause the pneumatic connections to switch so that A is connected to D and B to C.

FIG. 9 shows pneumatic or fluidic resistor symbol. A pneumatic resistor is a flow restriction in the line and is used to provide a pressure difference between A and B or to limit air flow between A and B.

CONTROL CIRCUIT ARRANGEMENT Referring to FIG. 10, there is shown a schematic diagram of a fluidic control circuit according to the present invention for controlling a multiphase gas blast electric circuit breaker 1.

Circuit breaker 1 comprises three phases or poles 111, lb and 1c and it is to be understood that each pole comprises at least one circuit interrupter and at least one isolator switch in an isolator chamber. Circuit breaker 1 further comprises an operating mechanism having a trip cylinder 1e and a close cylinder 1 f which are adapted to be supplied with pressurized gas, as hereinafter explained, from a low pressure (about 400 psi) gas supply tank 1d to trip and to close the circuit breaker. When circuit breaker l is closed, the isolator switch members in poles la lb and 1c are normally all closed and the isolator chambers are depressurized. When circuit breaker 1 is tripped open, the isolator switch members are normally all open and the isolator chambers are pressurized to about 370 psi from tank 1d.

The fluidic control circuit shown in FIG. 10 employs fluidic components shown in FIGS. 1 through 9 and the same nomenclature is used in FIGS. 1 through 10 for similar components.

Means are provided to furnish a source or supply of very low pressure gas (about 10 to 20 psi) for operation of the fluidic control circuit and such means take the form of a fluidic gas supply tank 3 into which gas is bled through a pressure regulating means 2 from tank 1d. Such pressure regulating means serves to maintain the pressure in tank 3 at a constant value although the air flow required by the fluidic circuit is not constant at all times. Gas is supplied to the fluidic con trol circuit through a fluidic supply line 5.

The fluidic control system comprises means to manually close and means to manually trip breaker 1. The manual close means or circuit comprises a push button 6 which allows supply gas from line to reach a preferenced flip-flop 7 and an OR-NOR gate 8. if the breaker supply pressure from tank 1d is sufficient to close pressure switch 11, elements 6, 7 and 8 in conjunction with a resistor 9 and a volume 10 will provide a fluidic pulse of predetermined duration to the four-way valve 12. Valve 12 then opens and supplies gas to close cylinder 1f of circuit breaker 1.

The manual trip means or circuit comprises a push button 13 which allows supply gas from line 5 to reach a preferenced flip-flop l4 and an OR-NOR gate 15. If the breaker supply pressure from tank M is sufficient to close pressure switch 18, elements 13, 14 and 15 in conjunction with a resistor 16 and a volume 17 will provide a fluidic pulse of predetermined duration to the passive OR device 19. The fluidic pulse is passed to the fluidic four-way valve 20. Valve then opens and supplies gas to trip cylinder le of circuit breaker 1.

Condition responsive means are provided for ignoring the manual close and manual trip commands if gas pressure in tank It! is too low to effect proper movement or operation of the isolator switch members of the circuit breaker. Thus, the pressure switches 11 and 18 can be independently adjusted so as not to operate (close) if pressure in tank id is below predetermined levels. If switches 11 and 18 do not close for this reason, OR-NOR gates 8 and 15, respectively, receive no control signal, the valves 12 and 20, respectively, remain closed and the cylinders If and 1e, respectively, are not actuated to operate breaker 1.

Condition responsive means such as feedback means are provided for sensing the condition of the isolator switches in the three circuit breaker poles 1a, and lb and 1c and such means comprise isolator control tubes 21a, 21b and 210 which I. which comprise a feedback logic system.

Means are provided for tripping circuit breaker 1 in the event that all poles do not operate together. The isolator control tubes 21a, 21b and 21c actuate pressure switches 32, 33 and 34, respectively. These provide inputs to the OR-NOR gates 26 through 31. If all phases 1a, lb, 1c are not all open or not all closed, a fluidic output signal is obtained on the NOR leg of gate 31. This signal is transmitted through a resistor 35 and a volume 36, to passive OR device 19 and to four-way valve 20. Valve 20 actuates the trip cylinder 1e of circuit breaker 1.

Heretofore, the set point of pneumatic lockout devices in pneumatic type control systems was partially dependent on the manner in which the operator pressed the pneumatic buttons. In the fluidic control circuit of the present invention, however, the operators command is first processed in the flip-flops 7 and 14, and then a signal is presented to the pressure switches 11 and 18 which are independent of the manner in which the operator pushes the buttons 6 and 13, respectively. In addition, the pulses which are provided by this circuit remove the trip or close command from the circuit breaker cylinders 1e and 1}", respectively, after a preset time, preventing a continuing signal to trip or close even though the operator continues to hold the buttons 13 or 6 down.

CONTROL SYSTEM OPERATION The manual close circuit operates as follows. Upon depression of close circuit push button 6, gas is supplied from fluidic supply line 5 to OR-NOR gate 8 and preferenced flip-flop 7. In the absence of any signal at the control ports of flip-flop 7, gas flow is obtained at the preferenced leg of flip-flop 7. If the supply pressure from tank 1d is not sufficient to close pressure switch 11, the flow from flip-flop 7 will be vented through switch 11 to the atmosphere and no further action will result. lf the supply pressure from tank 1d is sufficient to close pressure switch 11, the flow from flip-flop 7 will pass to the control input of OR-NOR gate 8 switching its output flow from its NOR leg to its OR leg. This flow passes to valve 12, which actuates cylinder 1f. Part of the gas from OR-NOR gate 8 bleeds back through resistor 9. After a time determined by the resistance of element 9 and the volume of element 10, the pressure in their connecting line builds up to a level sufficient to switch flip-flop 7 to its unpreferenced leg. The control signal to OR-NOR gate 8 is then removed and its output returns to its NOR leg to remove the signal from valve 12. An additional command cannot be obtained unless the operator releases push button 6 and depresses it again. This is the only way flow can be reestablished in the preferenced leg of flip-flop 7.

The manual trip circuit operates in a manner similar to manual close circuit except that its signal passes through passive OR device 19. Passive OR device 19 delivers a signal to valve 20 upon either a manual command from trip circuit push button 13 or upon a command from the feedback logic initiated in the isolator control tubes 21a, 21b and 21c.

One or more open breaker phases 1a, lb or 1c is detected by pressure in its associated isolator control tubes 21a, 21b or 21c. This pressurizes line 23 through one or more of the check valves 22 and opens pressure switch 25. Supply flow is provided through pressure switch 25 to each of the gates 26 through 31.

Each phase which is open opens its corresponding pressure switch 32, 33 and 34, thereby switching the flow in the corresponding OR-NOR gate 26, 27, or 28 to its OR leg. if all phases are open, the output of each of gates 26, 27 and 28 is at the OR leg. Since there is no output at any of the NOR legs of 26, 27, 28, there is no pressure on the inputs of gate 30 and its output is from its NOR leg. Thus, the NOR output of gate 30 represents all phases open. This causes the output of gate 31 to be at its OR leg, causing no signal to trip breaker 1.

lf breaker l is closed, and all phases are closed, lines 21a, 21b and 210 depressurize, but line 23 remains temporarily pressurized due to the check valves 22. However, pressure switches 32, 33 and 34 close, allowing the outputs of gates 26,

27 and 28 to return to their respective NOR legs. Since no output is present at the OR legs of gates 26, 27 or 28, gate 29 has a zero input signal and its output is at its NOR leg. Thus, a NOR output at gate 29 represents all phases closed. This causes gate 31 to have its output on its OR leg, causing no signal to trip the breaker. Eventually, the pressure at line 23, bleeding to atmosphere through resistor 4, drops low enough to close switch and the logic system is turned off.

lf a malfunction occurs such that at least one isolator switch of poles 10, lb or 1c is open and at least one is closed, line 23 will be pressurized thereby opening pressure switch 25 and supplying gas to the gates 26 through 31. At least one of the switches 32, 33 or 34 will be open and at least one will be closed. At least one of the gates 26, 2 7 or 28 will have an OR output and at least one will have a NOR output. Both gates 29 and 30 will have OR outputs. Thus, gate 31 will have a NOR output which will flow through resistor 35. After a predetermined time, volume 36 will be pressurized sufficiently to cause passive OR device 19 to actuate valve 20. This auxiliary trip command will continue as long as all breaker poles la, lb and 1c are not in the same state of being open or closed. The function of resistor 35 and volume 36 is to cause a slight delay in the auxiliary trip command. During any breaker operation, there are slight time differences in the operation of the poles. This may cause a momentary output at gate 31. As soon as all 'poles operate (a fraction of a second), the output at gate 31 will be deflected to its OR leg. The function of resistor 35 and volume 36 is to prevent the transmission of the momentary .pulse from gate 31 to circuit breaker trip cylinder 1e.

Thepressure switches 32, 33 and 34 could be normally open instead of normally closed and the system would :perform substantially as described.

Furthermore, different fluidic component arrangements could be devised to perform the aforedescribed functions in the manual trip and close circuits.

Pressure switches 11 and 18 may be physically located immediately after the push buttons or immediately before the four way valves instead of between the flip flops and OR-NOR gates as shown but operation would not be as good.

- A"different means could be used to sense the state of the breaker phases la, 1b and 1c. For example, instead of gas operated pressure switches 32, 33 and 34, switches which sense motion of some part of the breaker mechanism may be used.

w -A different method of generating a gas supply for operation of the fluidic control circuit could be used instead of bleeding gas from tank 1d into tank 3 through pressure regulator 2.

Breferenced flip-flops 7and 14 may be replaced with an equivalent fluidic circuit comprising two or more OR-NOR ga ,v

-, Since some commercially available OR-NOR gates have either the NOR or the OR leg unavailable for connections, the above fluidic circuits may be constructed using these devices but will require a greater number of gates.

Rreferenced flip-flops 7 and 14 may be replaced with an equivalent circuit comprising an unpreferenced flip-flop and means for preferencing said flip-flop.

,F inally, although the present invention is disclosed for use with a multiphase circuit breaker having a plurality of movable,is olating switch members, it is to be understood that a fluidiccontrol circuit according to the invention could be used to control a device other than a circuit breaker and such a device could have a greater or lesser of members which are movable to appropriate operating positions.

We claim:

. 1;. In a fluidic control circuit for controlling a pair of alternai ely QBFEa iY fluidi va e ..wh chn rma lvs t m ement of a member to an appropriate operating position:

a fluidic gas supply for operating said fluidic control circuit; .j manually .operable fluidic means for providing a fluidic pulse from saidfluidic gas supply to effect operation of said :fluidicvalv es alternatively;

condition responsive means responsive to a condition which would prevent normal'movement of said member, said condition responsive means preventing said manually operable fluidic means from providing a pulse;

and position responsive means responsive to the position of said member to effect operation of one of said pair of fluidic valves in the event that said member is not in an appropriate operating position.

2. A control circuit according to claim 1 wherein said manually operable fluidic means comprises a fluidic flip-flop element, means for effecting preferencing of said flip-flop element, and a fluidic OR-NOR gate and a push button for connecting them to said fluidic gas supply so that a fluidic pulse of predetermined duration is produced;

and wherein said position responsive means comprises means for sensing member position and for controlling a feedback logic system which effects operation of one of said pair of fluidic valves.

3.ln a fluidic control circuit for controlling a pair of alternatively operative fluidic valves which normally effect simultaneous movement of a plurality of members to appropriate operating positions by controlling an operating gas supply to operating cylinders which operate said members:

a supply of fluidic gas for operating said fluidic control circuit;

first manually operable fluidic means for providing a fluidic pulse from said fluidic gas supply to effect operation of one of said fluidic valves;

second manually operable fluidic means for providing a fluidic pulse from said fluidic gas supply to effect operation of the other of said fluidic valves;

condition responsive means responsive to the pressure of said operating gas supply for preventing either of said first and second manually operable fluidic means from providing its pulse in the event said pressure is below a predetermined level; I and position responsive means responsive to the positions of said members to effect operation of one of said pair of fluidic valves in the event that all of said members are not in their appropriate operating positions.

4. A control circuit according to claim 3 wherein said position responsive means comprises means for sensing member position and for controlling a feedback logic system which effects operation of one of said pair of fluidic valves.

5. A control circuit according to claim 4 wherein each 0 said manually operable fluidic means comprises at least one fluidic flip-flop element, means for effecting preferencing of said flip-flop element, and at least one fluidic OR-NOR gate and a push button for connecting them to said fluidic gas supply so that a fluidic pulse of predetermined duration is provided.

6. In a fluidic control circuit for operating a gas blast circuit breaker which has a supply of operating gas, a close cylinder and a trip cylinder, and an isolator chamber and an isolator switch for each pole, and wherein each isolator chamber is adapted to be pressurized when its isolator is open and to be depressurized when its isolator is closed:

a supply of fluidic gas for operating said fluidic control circuit; first and second fluidic valves for controlling said trip cylinder and said close cylinders, respectively; first and second manually operable fluidic means for providing a fluidic pulse to effect operation of said first and second fluidic valves, respectively; condition responsive means responsive to the pressure .of said operating'gas supply for preventing said first and second manually operable fluidic means from providing their pulses to their respective fluidic valves in the event gas supply pressure is below a predetermined level; and and position responsive means responsive to the positions of said isolators to effect operation of said first fluidic valve in the event that all of said isolators are not in the same position.

7. A control circuit according to claim 6 wherein said position responsive means comprises means responsive to pressure in said isolator chambers to detect isolator position and further comprises a feedback logic means for effecting operation of said first fluidic valve.

8. A control circuit according to claim 7 wherein each of 

